SAM Prelim

Bit

The smallest unit of data that a binary computer can recognize (a single 1 or 0)

Byte

8 bits

Numbering System

A way of representing numbers

Decimal Numbering System

Uses 10 symbols (0-9)

Binary Numbering System

Uses only two symbols (1 and 0) to represent all possible numbers

ASCII (American Standard Code for Information Interchange

Coding system traditionally used with personal computers.

EBCDIC (Extended Binary-Coded Decimal Interchange Code)

Developed by IBM, primarily for mainframe use

Unicode

Newer code (32 bits per character is common); universal coding standard designed to represent text-based data written in any ancient or modern language

Graphics

Still images such as photos or drawings

Bitmapped Images

A variety of bit depths are possible (4, 8, 24 bits)

Audio Data

Must be in digital form in order to be stored on or processed by a computer

Video Data

Displayed using a collection of frames, each frame contains a still image

Machine Language

Binary-based language for representing computer programs the computer can execute directly

System Unit

The main housing of a computer

CPU (Central Processing Unit)

Circuitry and components packaged together and connected directly to the motherboard

Dual-core CPU

Contains the processing components (cores) of two separate processors on a single CPU

Quad-core CPU

Contains 4 cores

CPU Clock Speed

One measurement of processing speed

Benchmark Tests

Can be used to evaluate overall processing speed

Bus

An electronic path over which data can travel

Bus Width

The number of wires in the bus over which data can travel

Arithmetic/Logic Unit (ALU)

Performs integer arithmetic and logical operations

Floating Point Unit (FPU)

Performs decimal arithmetic

Control Unit

Coordinates and controls activities

Pre-fetch Unit

Tries to fetch data and instructions before they are needed from cache or RAM

Decode Unit

Translates instructions so they are understood by the control unit, ALU, and FPU

Internal Cache and Registers

Store data and instructions needed by the CPU

Bus Interface Unit

Allows the core to communicate with other CPU components

System Clock

Timing mechanism within the computer system that synchronizes the computer’s operations

Machine Cycle

The series of operations involved in the execution of a single machine level instruction

Memory

Refers to chip-based storage

RAM (Random Access Memory)

Computer’s main memory

Registers

High-speed memory built into the CPU; used by the CPU

ROM (Read-only Memory)

Non-volatile chips located on the motherboard into which data or programs have been permanently stored

Flash Memory

Type of nonvolatile memory that can be erased and reprogrammed

Heat

A continuing problem for CPU and computer manufacturers

Fans

Used on most personal computers

Heat Sinks

Small components typically made out of aluminum with fins that help to dissipate heat

Water Cooling Systems

Cool the computer with liquid-filled tubes

Expansion Slot

A location on the motherboard into which expansion cards are inserted

Expansion Card

A circuit board used to add additional functionality or to attach a peripheral device

Expansion Bus

Connects the CPU to peripheral (typically input and output) devices

Memory Bus

Connects CPU directly to RAM

Frontside Bus

Connects CPU to I/O bridge

Port

A connector on the exterior of a computer’s system unit to which a device may be attached

Nanotechnology

The science of creating tiny computers and components less than 100 nanometers in size

Quantum Computing

Applies the principles of quantum physics and quantum mechanics to computers

Cases

Influences the motherboard form factor choice. Must allow for good airflow. Available in different sizes.

Power Supplies

Provides power to all computer components.

Motherboards

The backbone of the computer. Interconnects computer components

CPU

The brain of the computer. Most processing is done by this

Cooling Systems

Dissipates the heat generated by computer components.

Adapter Cards

Extend computer functionality. Adapter Cards connect to the motherboard through Expansion Slots

Video Ports

Connects a video system to an external display device such as a monitor or projector

Device

DVD drive, flash memory card reader, etc.

Medium

Is inserted into the device to be used

Storage Devices

Are typically identified by a letter, can be internal, external, or remote, are nonvolatile

Logical File Representation

The user’s view of the way data is stored

Physical File Representation

The actual physical way the data is stored on the storage media as viewed by the computer

File

Anything stored on a storage medium, such as a program, document, digital image, or song

Filename

Name given to a file by the user

Folder

Name place on a storage medium into which files can be stored

Hard Drive

Used to store most programs and data

Magnetic Hard Drives

Use metal hard disks. Read/write heads magnetize particles to represent the data’s 0s and 1s

Solid-state Drives (SSD)

Use flash memory technology, use less power and have no moving parts, particularly appropriate for portable computers

Disk Access Time

Total time that it takes for a hard drive to read or write data. Consists of seek time, rotational delay, and data movement time

Disk Cache

Dedicated part of RAM used to store additional data adjacent to data retrieved during a disk fetch to improve system performance

Hybrid Hard Drive

Combination of flash memory and magnetic hard drive. Uses flash memory for cache. Allows encryption to be built into the drive

Partitions

Logically divides the physical capacity of a single drive into separate areas

File System

Determines the cluster size, maximum drive size, and maximum file size. FAT, FAT32, and NTFS

Optical Discs

Store data optically (using laser beams). Divided into sectors like magnetic discs but use a single spiral track. Data is stored in 0s and 1s

Pits and Lands

Are used to represent 1s and 0s, the transition between a pit and land represents a 1; no transition represents a 0

Read-only

Surface is molded or stamped to represent the data

Recordable or Rewritable

Reflectivity of the surface is changed by a laser

Optical Drives

Designed for the type of disc: CD, DVD, or Blu-Ray Disc (BD). Can be read-only, recordable, or rewritable. Downward compatible. Can support single or dual-layer discs

Burning

Recording data onto a disc

CD Discs

Use infrared lasers; hold 650 MB

DVD Discs

Use red lasers; hold 4.7 GB (single-layer)

BD Discs

Use blue-violet lasers; hold 25 GB (single-layer)

Read-only Discs

Can be read from, but not written to, by the user

Recordable Disc

Can be written to, but cannot be erased and reused

Rewrtitable Disc

Can be recorded on, erased, and overwritten just like magnetic discs

Chip-based Storage Medium

No moving parts so more resistant to shock and vibration, require less power, make no sound. Solid-state storage system

Flash Memory Card

A small card containing one or more flash memory chips, controller chips, and metal contacts to connect the card to the device or reader

USB Flash Drives

Consist of flash memory media and a reader in a single self-contained unit

Remote Storage

Using a storage device not directly a part of the computer being used

Network Storage

Via a local network

Network Attached Storage (NAS)

Connected directly to a network

Storage Area Network (SAN)

Separate network of hard drives or other storage devices which is attached to the main network

Smart Card

Credit card-sized piece of plastic that contains some computer circuitry (processor, memory, and storage)

Holographic Storage

Store data as holograms. An emerging type of 3D storage technology. Uses two blue laser beams to store data in three dimensions

Storage Server

Hardware device containing multiple high-speed hard drives

RAID (Redundant Arrays of Independent Discs)

Method of storing data on two or more hard drives that work together to do the job of a larger drive

RAID 0

Disk striping (spread files over two or more hard drives)

RAID 1

Disk mirroring (duplicate copy). Other level use a combination of striping and mirroring

Magnetic Tape

Plastic tape with a magnetizable surface that stores data as a series of magnetic spots

Pointing Devices

Used to select and manipulate objects. Used to input data. Used to issue commands to the computer

Mouse

A common pointing device that the user slides along a flat surface to move a pointer around the screen and clicks its buttons to make selections

Stylus

Pen-like device used to draw or write electronically on the screen. Also called a digital pen, electronic pen, tablet pen

Digital Form

Used to input handwritten data into the computer and then convert it to editable text